The present invention provides a low latency error correction mechanism for high data rate transmissions over multiple traffic channels in a wireless communication system.
It is known to include forward error correction (xe2x80x9cFECxe2x80x9d) coding and decoding to information signals that are to be transmitted over a wireless channel. Forward error correction, generally speaking, introduces predetermined redundancy into an information signal to permit a receiver to identify and perhaps correct errors that may have been introduced by a transmission medium. For example, the known IS-95 standard for code division multiple access cellular communication specifies a type of convolutional code for each traffic channel transmitted from base station to mobile station or vice versa.
Recently, it has been proposed to provide high data rate exchanges over a wireless communication system. Such high data rate exchanges may be used, for example, to facilitate data transfer for computing applications or for video conferencing applications. In one such proposal, a high rate data signal may be communicated to a receiver over a plurality of parallel traffic channels. For example, the recently proposed IS-95 B standard proposes use of parallel CDMA channels each having a data rate of 9.6 KB/s to provide a higher data rate communication. In such systems, a high rate data signal is demuliplexed into a plurality of lower rate data signals and each of these signals is processed in an independent traffic channel. Thus, each lower rate data signal has FEC applied to it.
Another example of a wireless CDMA system providing multiple parallel traffic channels for high data rate exchange may be found in the copending patent application xe2x80x9cProtocol Conversion and Bandwidth Reduction Technique Providing Multiple nB+D ISDN Basic Rate Interface Links Over a Wireless Code Division Multiple Access Communication System,xe2x80x9d Ser. No. 09/030,049 filed Feb. 24, 1998 the disclosure of which is incorporated herein.
Wireless communication channels are inherently xe2x80x9cnoisyxe2x80x9d due to channel impairments caused by atmospheric conditions, multipath effects, co-channel interference and the like. Particularly if used for computing applications, where executable content may be expected to be exchanged over traffic channels, the need for powerful FEC techniques will continue to be prevalent.
Use of more powerful FEC techniques in such wireless systems may increase the latency of data requests. For example, the known turbo codes require large blocks of data to be received entirely by a decoder before decoding can begin. Latency refers generally to the delay that extends from the time a request for data is issued by a user and the time when data responsive to the request is presented to the user. FEC introduces decoding delays at a wireless receiver and, thus, contributes to latency.
There is a need in the art for a wireless communication system that provides high data rate exchange having high quality FEC with low latency.
Embodiments of the present invention provide a transmitter/receiver system for high data transfer in a wireless communication system in which a physical layer processor comprises an FEC coder, a demultiplexer and a plurality of modem processors. The FEC coder applies error correction codes to the high data rate signal. Thereafter, the demultiplexer distributes portions of the coded high data rate signal to the modem processors. Each modem processor processes its respective portion of the coded signal for transmission in an independent channel.